Anvil impact tool



Jan. 26, 1965 R. K. WILMER ANVIL IMPACT TOOL.

I 3 Sheets-Sheet 1 Original Filed Aug. 25, 1960 INVENTOR RICHARD K. W/L

mifg mm m HIS AGENT Jan. 26, 1965 R. K. WILMER 3,167,135

ANVIL IMPACT TOOL Original Filed Aug. 25. 1960 3 Sheets-Sheet 2 FIG. 3A

INVE NTOR RICHARD K WIL MEI? HIS AGENT Jan. 26, 1965 R. K. WILMER3,167,135

.ANVIL IMPACT TOOL Original Filed Aug. 25. 1960 5 Sheets-Sheet 3INVENTOIR RICHARD K ML 5 CQWQQQ wa HIS AGENT United States PatentOfitice 3,167,135 Patented Jan. 26, .1965

This invention relates to tools and more specifically to an impact toolhaving an axially movable anvil, such as a nail driver.

This application is a continuation of my copending application, SerialNo. 51,998, filed August 25, 1960, now abandoned, and assigned to thesame assignee as the present application.

At the present time, a conventional nail driver normally has a springbiased sleeve to receive the head of a nail which is contacted by aresiliently mounted anvil. A reciprocal piston repeatedly strikes theanvil to drive the nail. When the nail head approaches the workpiece,the sleeve yields against the force of the spring so that the nail canbe driven flush with the outer surface of such workpiece. With this typeof nail driver, it is diflicult to start driving a nail because theoperator has to meter controlling pressure fluid for the. impact forceof the tool by progressively displacing a tool trigger to start with asmall amount of power and to progressively increase such power as thenail is driven. during the remainder of the driving operation becausethe operator has to move the tool forward with the nail as it is beingdriven. In addition, when a coil spring is used to bias the sleeve,inertia tends to break the first of the coils and the rear end of thesleeve may then impact against a shoulder on the anvil and causebreakage.

A nail driver constructed according to this invention is comprised of abarrel with a handle secured thereto. A valve is secured in the rear endof the barrel that Thereafter, it is diflicult to guide the nail isdisposed in a blind bore of the handle which sur- Further, in accordancewith the present invention, the

tool remains stationary during the entire nail driving operation asdistinguished from the aforementioned conventional nail driver in whichthe tool fol-lows the nail 7 towards the workpiece. As will be seen, asleeve is fixed to the end of the barrel to receive a nail to be drivenand locks a spring in the end of the barrel bore to engage a head on theanvil to limit its movement when the nail is fully driven and to act asa buffer. The nail is placed against the workpiece and into a nosepieceor sleeve that is also placed against the workpiece, thus, the length ofthe nail limits the forward position of the anvil. At the start of thedriving operation, the limited piston stroke is relatively short, andtherefore, the anvil is struck lightly asis desirable to start the nailand which approximates the use of a hand wielded hammer. However, as thenail is driven, the piston stroke progressively increases toprogressively increase the impact force on the anvil.

An object of this invention is to provide an impact tool having aprogressively increasing force output that may be usedby an unskilledoperator.

Another object of this invention is to provide an impact tool having aprogressively increasing force output and is maintained in a fixedposition during each complete driving operation. t

Another object of the invention is to provide an impact tool having ananvil that is repeatedly struck with progressively increasing force.

Another object of the invention is to provide an impact tool which isinoperative or fully operative, and has an anvil that is repeatedlystruck with progressively increasing force by a reciprocating pistonwhen operating.

Another object of the invention is to provide an impact tool which isinoperative or fully operative, and has an anvil that is repeatedlystruck with progressively increasing force by a reciprocating pistonwhen operating, and includes a valve having a hollow valve member thatautomatically controls the flow path of the pressure fluid which drivesthe piston; the hollow valve member providing a path by its bore whichforms a portion of the normal path of reciprocation of the piston.

This invention contemplates an impact tool that is held stationaryrelative to a workpiece during its operating cycle, comprising a barrel,a sleeve connected to the barrel to be placed in contact with theworkpiece, an anvil movable in the barrel, apiston reciprocated in thebarrel for repeatedly striking the anvil to drive the anvilprogressively into the sleeve and toward the workpiece, and valve meansin the barrel to. provide pressure fluid for reciprocally moving: thepiston.

The foregoing and other objects and advantages of the invention willappear more fully hereinafter from a consideration of the detaileddescription which follows, taken together with the accompanyingdrawingswlierein a single ernbodiment of the invention is illustrated byway of example. It is to be expresslyunderstood, however, that thedrawings are for illustration purposes only an dare not to be construedas defining the limits of the invention.

FIGURE 1. is an elevational view ofa tool constructed according to theinvention with the barrel and forward portion of the handle thereof invertical section,

FIGURE'Z is an enlarged sectional. view taken on line 2-2 of FIGURE 1, 1

FIGURE 3 is taken on line 3-3-of FIGURE 2 and is a sectional viewthrough the connection of the barrel and handle, and includingthevalveof'the' tool,

FIGURE 3A is a sectional view taken: on line- 3"3 of FIGURE 2 and is;similar toFIGURE .3 Withthe valve in an adjusted position, and

FIGURES 4 and 4A are sectional viewstaken on line 44 of FIGURE 2 and?are similar to FIGURES 3* and 3A.

Referring now to the drawings, and specifically to FIGURE 1, anovel toolin the form of a nail driver is constructed according to the inventionandcomprises a barrel 20 threadedly inserted; and locked in a blind bore1 2 of a handle 10 with a. fitting 14 adapted. to be connected to asource'of pressure fluid (not shown) for operation. A trigger 16 ismounted on thehandle 10 and is manually operable for openingand closingavalve (not shown) in an inlet supply line or. passage 18to controltheflow of pressurefluidto the blind bore 12. The barrel 20has an axialthrough here 22 with a rear counterbore 24rd: receiving and liousi'ng avalve 80. Part of the valve 80 extends to and abuts the base of theblind bore 12 in handle 10, and with bore 12 forms an annular pressurefluid cham'lier 58in communication with passage 18. The forwardendofthe-bore 22 is counterbored at 26 for receiving a resilientmember-or spring 28 with a centralopening 30 coaxial with bore 221 butof a reduced diameter. The 'spring'28i'sdocked in couiiterbore' i 26 bya nosepiece or sleeve 32 with an axial bore 34 that is coaxial with bore22 and of substantially the same diameter as the central opening 30 ofspring 28. The bore 34 has an undercut for permitting slight axialmovement of the inner portion of spring 28. When the tool is *to beused, nosepiece 32 is placed against the work with a nail to be drivendisposed in bore 34.

The barrel 20 has three axial bores 36, 40 and 44, angularly spaced fromone another and disposed around bore 22, that extend forwardly from thebase of counterbore 24. A port 38 connects passage 36 to the frontportion of bore 22 of the barrel 28 while passage 44 is connected to therear portion of bore 22 by axially spaced ports 46 and 48. Exhaustpassage 40 has an exhaust port 42, extending through the wall of barrel20, that is covered by a perforated annular skint 54 also covering theconnection between the handle 10 and barrel 20.

An anvil 50, with an enlarged head 52, is supported in opening 30 ofspring 28 and is axially movable in bore 22. A piston 54 is reciprocallydriven by the pressure fluid to repeatedly strike anvil t driving itforwardly into bore 34 to drive a nail therein into a workpiece. Whenpiston 54 is driven backwardly into bore 62 of a valve member 60 ofvalve 80, member 64 then shifts to its forward position to connectpressure fluid behind piston 54 for driving it forwardly into contactwith anvil head 52 to hammer anvil 50' forwardly. As this is repeatedand anvil 50 moves progressively into bore 34, it may be readilyvisualized that the length of the stroke of piston 54 increases as willits impact force. When the nail is flush with the workpiece, anvil 50 isin its forward position with its head 52 in contact with spring 28.Spring 28 acts as a shock absorber or buffer becauseits inner coil ispermitted to flex into the undercut of bore 34.

The valve 80- alternates the flow of pressure fluid between two flowpaths to reciprocally drive piston 54, and has a divided body 82 with abore 84 coaxial with bore 22 of barrel 20. The movable valve member 60is reciprocally retained in the bore 84 with its bore 62 also coaxialwith bore 22. 'There is an annular groove 64 in the outer surface ofvalve member 60, spaced forwardly from an annular flange 66 having afront face 68 and a rear face 70. Bore 84 has an annular groove 86, forthe flange 66, that has a front face 88 and rear face 90 for contactingflange faces 68 and 70, respectively, to limit the axial movement ofmember 60.

Theportion of bore 84 rearward of member 60 is reduced to approximatelythe diameter of bore 22 or 62 and forms a pressure pocket92 inrestricted communication with the chamber 48 through a small port 94.

7 Pressure fluid from chamber 58 also enters the bore 62 through a port96 that is uncovered when member 60 is in its forward position as shownin FIGURES 3A and 4A,

a then flows into bore 62 to drive the piston 54 forwardly plete theexhaust passage.

The axially reciprocal valve member 66 is maintained in its forwardposition by the force of the pressure fluid in pocket 92. However, aspiston 54 passes port 46 or ports 46 then 48, pressure fluid in bore 22enters passage 44. Passage 44 is connected to the front of annulargroove 86 by a passage 106 in valve body 82, and pressure fluidtherefrom acting between faces 68 of flange 66 and 88 of groove 86 kicksmember 60 backwardly toward its second position. At this'time, the areain groove 86 between its face 90 and face 70 of flange 66 reduces andexhausts through passage 104.

With valve member 60 in its rearward position, as shown in FIGURES 3 and4, port 96 is closed and pressure fluid from chamber 58 entering port 26flows through a passage 108 to annular groove 86 and to bore 84 betweengrooves 86 and 1%. While pressure fluid from passage 186 merely kicksmember 64? back to uncover passage 108 at groove 86, the pressure fluidfrom passage 168 then drives member 60 to its rearrnost position.

Groove 64 of member 68 now laps passage 108 at bore 84 and annulargroove 180, therefore, pressure fluid passes through passages 98 and 36to the front end of bore 22 through port 38 to drive piston 54rearwardly. With valve member 60 in its rearmost position, annulargroove 182 is uncovered and the area behind piston 54 exhausts throughpassages 194 and to exhaust port 42.

As piston 54 being driven rearwardly enters bore 62 of valve member 66,the exhaust path of bore 62 and pocket 92 through annular groove 10?. isclosed and the fluid therein is trapped and compressed by piston 54. Thecompressing fluid in pocket 92 not only acts as a buffer for rearwardlymoving the piston 54 but will provide sufficient force against the backsurface of member to move it forwardly and return it to its position asshown in FIGURES 3A and 4A. Additionally as piston 54 enters bore 62, ituncovers port 48 or ports 48 and 46, thus, connecting passage 44 to port38 by bore 22. Therefore, as member 66 moves forwardly, groove 64reconnects passage 36 for exhausting, and pressure fluid from the areabetween faces 68 and 88 of flange 66 and groove 86, respectively, isexhausted.

Therefore, the novel device as described herein, includes a pressurefluid driven motor having valve means to automatically reciprocate thepiston thereof for progressively driving an anvil toward a workpiece andinto a sleeve that is connected to the end of the motor and isplaced incontact with such workpiece prior to operation of the device. 1

Although but a single embodiment of the invention has been illustratedand described in detail, it is to be expressly understood that theinvention is not limited thereto. Various changes may also be made inthe design and arrangement of the par s without departing from thespirit and scope of the invention as the same will now beunderstood bythose skilled in the art.

I claim: V

1. An impact tool that is held stationary relative to a workpiece duringits operating cycle, comprising a barrel, a sleeve connected to thebarrel to be placed in contact with the workpiece, an anvil movable inthe barrel,

a piston reciprocated in the barrel for repeatedly striking the anvil todrive the anvil progressively into the sleeve and toward the workpiece,and valve means in the barrel to provide pressure fluid for reciprocallymoving the piston.

2. An impact tool comprising a barrel, a sleeve connected to the barrelto be placed in contact with a workpiece, a valve disposed in the barrelto receive pressure fluid, a hollow valve member movable in the valvebetween two positions to provide pressure fluid from the valve forreciprocating a piston, an anvil movable axially in the barrel, and apiston reciprocated in the barrel between a position in the valve memberand a position contacting'the anvil to repeatedly strike and drive theanvil progressively into the sleeve. 7

3. An impact tool comprising a barrel, a sleeve 'connected to the barreland to. be placed in contact with a workpiece, a valve disposed in thebarrel to receive pressure fluid, a hollow valve member movable in thevalve between two positions to provide pressure fluid from the valve forreciprocating a piston, an anvil having a head and being'movable axiallyin the barrel, a piston reciprocated in the barrel beteween a positioninthe valve member and a position contacting the anvil head torepeatedly strike and drive theanvil progressively into the sleeve, andresilient means disposed between the sleeve and the anvil head to limitthe movement of the anvil into the sleeve and to butter the anvil headwhen the anvil reaches its limit.

4. An impact tool comprising a barrel, a valve disposed in the barrel toreceive pressure fluid, a hollow valve member movable in the valvebetween two positions to provide pressure fluid from the valve forreciprocating a piston, an anvil axially movable in the barrel, and apiston reciprocated in the barrel between a position in the valve memberand a position contacting the anvil to drive the anvil progressivelyaway from the valve.

5. A tool comprising a barrel, a hollow valve member reciprocal in thebarrel, an anvil movable axially in the barrel and to be drivenprogressively away from the valve member, a piston movable axially inthe barrel and into the hollow valve member, and means for driving thepiston out of the hollow valve member into engagement with the anvilwith progressively increasing force determined by the relative positionsof the anvil to the valve member.

6. A tool comprising a barrel, a valve in the barrel, a hollow valvemember reciprocal in the valve, an anvil slidable in the barrel and tobe driven progressively away from the valve, a piston reciprocal in thebarrel between two positions within the hollow valve member and engagingthe anvil, and means when the piston enters the hollow valve member formoving the member to provide pressure fluid for moving the piston intoengagement with the anvil with progressively increasing force determinedby the relative positions of the anvil to the valve.

7. A tool comprising a barrel, a valve disposed in the barrel, a hollowvalve member movable in the valve between two positions, an anvilslidable axially in the barrel, a piston reciprocal in the barrel torepeatedly strike the anvil with progressively increasing force, meansfor moving the hollow valve member to one of its positions for admittingpressure fluid through the valve and the barrel in front of the pistonto move the piston toward the rear end of the barrel and for exhaustingthe fluid behind the piston to atmosphere as the piston moves toward therear end of the barrel, and the piston entering the hollow valve membercompressing fluid in the valve that acts to move the hollow valve to theother of its positions to provide pressure fluid through the valve todrive the piston out of the hollow valve member to strike the anvil.

8. An impact tool comprising a barrel, a valve disposed in the barrel toreceive pressure fluid and having a bore closed at one end to form apocket, a hollow valve member movable in the valve between two positionsto provide pressure fluid from the valve for reciprocating a piston andto the pocket when the piston moves away from the valve, an anvilaxially movable in the barrel, and a piston reciprocated in the barrelbetween a position in the valve member and a position contacting theanvil to drive the anvil progressively away from the valve, the pistontrapping and compressing the fluid in the pocket as it moves into thevalve member to bufler the piston and to move the valve member forproviding pressure fluid to move the piston into contact with the anvil.

9. An impact tool comprising a barrel, a sleeve connected to the barrelto be placed in contact with a workpiece, a valve disposed in the barrelto receive pressure fluid and having a bore closed at one end to form apocket, a hollow valve member movable in the valve between two positionsto provide pressure fluid from the valve for reciprocating a piston andto the pocket when the piston moves away from the valve, an anvil havinga head and being movable in the barrel, a piston reciprocated in thebarrel between a position in the valve member and a position contact theanvil head to repeatedly strike and drive the anvil progressively intothe sleeve, the piston trapping and compressing the fluid in the pocketas it moves into the valve member to butter the piston and to move thevalve member for providing pressure fluid to move the piston intocontact with the anvil, and resilient means disposed between the sleeveand the anvil head to limit the movement of the anvil into the sleeveand to buffer the anvil head when the anvil reaches,

BROUGHTON G. DURHAM, Primary Examiner. KARL I. ALBRECHT, Examiner.

1. AN IMPACT TOOL THAT IS HELD STATIONARY RELATIVE TO A WORKPIECE DURINGITS OPERATING CYCLE, COMPRISING A BARREL, A SLEEVE CONNECTED TO THEBARREL TO BE PLACED IN CONTACT WITH THE WORKPIECE, AN ANVIL MOVABLE INTHE BARREL, A PISTON RECIPROCATED IN THE BARREL FOR REPEATEDLY STRIKINGTHE ANVIL TO DRIVE THE ANVIL PROGRESSIVELY INTO THE SLEEVE